
function setCookie(cname,cvalue,exdays){
    var d=new Date();
    d.setTime(d.getTime()+(exdays*24*60*60*1000));
    var expires = "expires="+d.toGMTString();
	document.cookie = cname+"="+cvalue+"; "+expires;
}  


function getCookie(cname){
    var name=cname+"=";
    var ca=document.cookie.split(";");
    for(var i=0;i<ca.length;i++){
        var c=ca[i].trim();
        if(c.indexOf(name)==0){
            return c.substring(name.length,c.length);
        }
    }
    return "";
}

function checkCookie(){
    var user=getCookie("username");
    if(username!=""){
        alert("欢迎"+username+"再次访问");
    }else{
        user=prompt("请输入你的姓名：");
        if(user!=""&&user!=null){
            setCookie("username",user,30);
        }
    }
}

function clickButton(){
    alert("按钮事件！");
}